Pneumatic tube system with stand-by blower

ABSTRACT

In a pneumatic tube system comprising one blower each for the vacuum intake air and the compressed air, a stand-by arrangement consisting of a stand-by blower, of two controlled valves and of four back-pressure valves is provided for increasing the operational reliability. Upon failure of one of the main blowers the supervisory elements associated with the main blowers serve to switch on the stand-by blower as well as the respective controlled valve. The corresponding back-pressure valves are opened or closed automatically by the air stream as produced by the stand-by blower.

United States Patent Buchwald et al.

Aug. 7, 1973 PNEUMATIC TUBE SYSTEM WITH STAND-BY BLOWER Inventors: Fritz Buchwald; Dieter Pienkny,

both of Berlin, Germany International Standard Electric Corporation, New York, NY.

Filed: Nov. 10, 1971 Appl. No; 197,328

Assignee:

Foreign Application Priority Data Nov. 23, 1970 Germany P 20 57 557.9

11.5. c1. 417/4, 417/286, 417/426 1111. c1. F041) 41/06 Field of Search 417/5, 426, 428, 417/286, 6, 4

References Cited UNITED STATES PATENTS 8/1952 Walker et,al.- 417/286 ll/l952 lsreeli 417/286 X Primary Examiner-Carlton R. Croyle Assistant Examiner-R. J. Sher Att0mey-C. Cornell Remsen, Jr. et al.

57 ABSTRACT 'In a pneumatic tube system comprising one blower 4 Claims, 2 Drawing Figures V1 10 7 20 Air Entrance 12 1 A I J ZSQZTfiZ 23 o m e V2 1 j"; .3 atri -@51 1E3] 2| Air Exit 5 PAIENIED 71m Air Entrance sum mi 2 FIG.I

INVENTORS FRITZ aucflwA 4 0 0/: ran P/ENK Y AGENT v PNEUMATIC TUBE SYSTEM WITH STAND-BY BLOWER Operational reliability of a pneumatic tube system largely depends on the kind of blower used for supplying the operating (driving) air. Therefore, if in pneumatic tube systems an interruption of work is to be avoided under all circumstances, it is necessary to provide a stand-by (reserve) blower which takes over automatically in response to the operation of a supervisory element indicating that the main blower has ceased to operate. If, in such a system, there is used a compressed-air blower as well as a vacuum intake air blower, it will happen in most cases that only one of these blowers alone will fail to operate. Thus, it is sufficient to provide one single stand-by blower for both operating processes, which is to take the place of the one blower that has failed to operate. Owing to the'oppositely directed modes of operation, however, the switching-on of a stand-by blower requires an individual connection of the air ducts which, in turn, requires a large number of controlled valves. The investment involved in controlling the switching-n of an individual blower may thus become equal or even higher than the inventment involved when providing a second stand-by blower.

It is the object of the invention to provide steps and measures with the aid of which this investment can be considerably reduced without affecting operational reliability.

The invention relates to a pneumatic tube system employing a vaccum intake air blower as well as a compressed-air blower for supplying the operating air, and in which, besides these blowers, there is also provided a stand-by blower.

The invention resides in the fact that one single stand-by blower, via respectively only one controlled valve and one back-pressure valve, is arranged parallel in relation to the. compressed-air blower as well as parallel in relation to the vacuum intake air blower, and also in the fact that a further separate. back-pressure valve is provided on the vacuum side of the vacuum intake air blower and on the compressed-air side of the compressed-air blower.

Since, as is well known, back-pressure valves are operated by the operating air, only two controlled valves are contained in the system, of which respectively one has to be operated upon the failure of a corresponding one of the operating air blowers. Appropriately, the controlled valve for compressed-air operation is arranged on the vacuum side of the stand-by blower,.and the one for vacuum operation is accordingly arranged on the compressed-air side. Further, back-pressure valves are arranged in the operating air ducts of the operating air blowers, i.e. one each in the operating air duct of the compressed-air blower on the compressedair side thereof and in the operating air'duct of the vacuum intake air blower on the vacuum side thereof.-

Upon failure of one of the operating air blowers during operation, it is effected that the stand-by blower is applied to the source of voltage, and that the particular one of the controlled valves is opened which is positioned in the air stream circuit of the blower which has failed to operate.

The invention will now be explained with reference. to the accompanying drawings FIG. 1 schematically showing the arrangement for two main blowers and one stand-by blower according to the invention and FIG. 2 showing a control circuit therefor.

The compressed-air blower M1 is positioned in the air duct extending between the air entrance 1 and the compressed-air connection 2 of the pneumatic tube system. In the same way the vacuum intake air blower M2 is positioned in the air duct extending from the vacuum connection 4 of the pneumatic tube system to the air exit 3. In each of these air ducts there is moreover, also arranged respectively one sound absorber (silencer) 5 or 6, and one air filter 7 or 8. The air'entrance sides of the blowers M1 and M2are in communication with one another by the air duct 10, and the air exit sides are in communication with one another by the air duct 11. In each these tubes or air ducts 10 and 11, near the air entrance or air exit respectively of the blowers M1 and M2, there is arranged one controlled valve V1 or V2; and near each of the two connecting ends serving the pneumatic tube system, there is-arranged one back-pressure valve 20 or 21 respectively. Between the connecting points 12 and 13 ofthevalves V1 and 20 on one hand, and of the valves- V2 and 21 on the other'hand, there are applied the air connections of the stand-by blower. M3, i.e. the air entrances to the air duct 10 connecting theair entrancesof the'blowers Ml andMZ, and the air exits to the air duct 1'13 connecting the air exits of the blowers.

The arrangement operates as follows: Normally, the blowers M1 and M2 are in operation. The compressedair blower Ml has its air intake at 1, and supplies compressed air to the pneumatic tube systemv at 2. Simi' larly, the vacuum intake airblower M2 has its operating air intake from the system at 4, and presses the latter out into the. open air at 3'. The controlled valves V1 and V2 are closed. Likewise closed. are: the backpressure valves 20 and 21, which are arranged in' the connecting air ductsl0 and 11-, because the stand-by blower M3 is inoperative; ln distinction thereto, the

back-pressure valves 23 in the vacuum air duct between 4 and 3 and the back-pressure valve 22. in. the compressed air duct between 1 and 2 are-open, becauseair streams flow in these air'ducts in the forward direction of these valves. Valves 22 and 23,. as shown, have control contacts 22a and 23a'respectively.

lf now'the blower Ml fails tooperate'then its supervisory element which may be an. indicator of the pneumatic-, voltage or'current-dependent type, will effectthe opening of the controlled valve V1 andtheconnection of the blower M3 to a source of voltage, e.g.,. the mains. See in this regard FIG. 2 to be described in greater detail below. Inside the air duct 1.0there exists atmospheric pressure up to point 20, so that the backpressure valve 20remains to be closed. The air stream.

caused by the blower M3 opens the back-pressure valve 21, and closes'22, so that no air can escape via the inoperative blower M 1. Accordingly, there is established a connection extending from 1' via the filter 7, the valve V1 the. blower M3, the back-pressure valve 21 which is opened by the air stream produced. by the blower M3, and the sound. absorbertsilencer) 6 to the compressed-air connection 2.

During normal operation the flaps of the backpressure valves 22 and. 23 are opened. and, consequently, also the contacts 22a and 23a. are open. As.

soon as the blower Ml fails to operate in. the embodi-- ment of FIG. 2, however, the back-pressure valve 22 as a practical matter becomes closed because of the absence of compressed air. On account of this, the contact 22a is actuated and the relay 30 is switched on (FIG. 2). The contacts 30a of this relay apply to the valve V1 the mains voltage, so that this valve will open. At the same time the fault-indicating lamp L1 is lit and thus indicates the failure of the blower M1. By means of a further contact 30b of the relay 30 the stand-by blower M3 is switched on to maintain the air supply for the pneumatic tube system.

if the blower M2 fails to operate, then the supervisory element thereof will effect the opening of the controlled valve V2, and the application of the blower M3 to the source of voltage. There is then produced an air stream flowing from the vacuum connection 4 via the air filter 8, the back-pressure valve 20, the blower M3, the controlled valve V2, via the sound absorber (silencer) 5, to the air exit 3. Since the back-pressure valves 21 and 23 are in the reverse direction with respect to air pressure, these valves are closed.

Specifically, in the event of failure on the part of blower M2, the contact 23a is closed in similar manner to closing of contact 22a in the example situation described above for blower M1 failing. By this, the relay 31 is energized, with the contacts 31a and 31b thereof applying the valve V2, the fault-indicating lamp L2, and the stand-by blower M3 to the mains voltage, and thereby effect a full change-over to stand-by blower operation.

The supervisory element indicates the failure of the respective blower also to an operator via the lamps L1 and L2, for enabling a quick removal of the fault and the switching back of the system to normal operation. It will be recognized that chiefly only two controlled valves are required, one in each main air duct, for safeguarding an unobjectionable stand-by operation with the aid of only a single stand-by blower. These valves V1 and V2 can be kept closed by the action of springs, and can be reopened by the action of electromagnets. It is simpler, however, for the valves V1 and V2 to be moved into their opened or closed conditions by the action of electric motors. This movement is then referred to as one effected with the aid of electromotive (electromotoric) slides. The costs involved are relatively low when consideringthe high operational reliability and the costs otherwise necessary for employing a second standby blower.

What is claimed is:

1. In a pneumatic tube system incorporating a main vacuum intake air blower as well as a main compressed air blower for supplying the operating air, and further incorporating a single stand-by blower, the arrangement comprising a first controlled valve and a first back-pressure valve for coupling said-stand-by blower in parallel relative to the main compressed air blower, a second controlled valve and a second back-pressure valve for coupling said stand-by blower in parallel relative to the main vacuum intake air blower, a third backpressure valve provided on the vacuum side of the main vacuum intake air blower and a fourth back-pressure valve provided on the compressed air side of the compressed air blower.

2. The arrangement according to claim 1 wherein said first controlled valve is arranged on the vacuum side of the stand-by blower, and said second controlled valve is arranged on the compressed air side of the stand-by blower.

3. The arrangement according to claim 2 whrein said third and fourth back-pressure valves comprise control means for detecting a failure of one of the main blowers and for activating said stand-by blower to an operative condition and the controlled valve associated with the failed main blower to an open condition, and thereby maintaining normal system operation via a single standby blower.

4. In a pneumatic tube system operating with both compressed air and vacuum connections, in which there is incorporated a main vacuum intake air blower coupled between the vacuum connection and a system air exit and a main compressed air blower coupled between a system air entrance and the compressed air connection, the arrangement comprising a single standby blower operatively coupled in said pneumatic system for maintaining system operation in substitution of either of said main blowers in the event of failure of either one of the latter, said stand-by blower being associated with said main compressed air blower by being coupled firstly in parallel to said main compressed air blower between said system air entrance and said compressed air connection, and being associated with said main vacuum intake air blower by being coupled secondly in parallel to said main vacuum intake air blower between said vacuum connection and said system air exit, said first parallel coupling including a first controlled valve coupled between the system air entrance and the air intake side of-said main compressed air blower and a first back-pressure valve coupled between the compressed air side of said main compressed air blower and said compressed air connection, said second parallel coupling including a second controlled valve coupled between the compressed air side of said stand-by blower and the system air exit and a second back-pressure valve coupled between said vacuum connection and the vacuum side of said stand-by blower, and further comprising control means, including third and fourth back-pressure valves coupled respectively between the compressed air side of said main compressed air blower and said compressed air connection and between said vacuum connection and the vacuum side of said vacuum intake air blower, for detecting a failureof one of the main blowers and for activating said stand-by blower to an operative condition and the controlled valve associated with the failed main blower to an open condition.

t t t I i 

1. In a pneumatic tube system incorporating a main vacuum intake air blower as well as a main compressed air blower for supplying the operating air, and further incorporating a single stand-by blower, the arrangement comprising a first controlled valve and a first back-pressure valve for coupling said stand-by blower in parallel relative to the main compressed air blower, a second controlled valve and a second back-pressure valve for coupling said stand-by blower in parallel relative to the main vacuum intake air blower, a third back-pressure valve provided on the vacuum side of the main vacuum intake air blower and a fourth back-pressure valve provided on the compressed air side of the compressed air blower.
 2. The arrangement according to claim 1 wherein said first controlled valve is arranged on the vacuum side of the stand-by blower, and said second controlled valve is arranged on the compressed air side of the stand-by blower.
 3. The arrangement according to claim 2 wherein said third and fourth back-pressure valves comprise control means for detecting a failure of one of the main blowers and for activating said stand-by blower to an operative condition and the controlled valve associated with the failed main blower to an open condition, and thereby maintaining normal system operation via a single stand-by blower.
 4. In a pneumatic tube system operating with both compressed air and vacuum connections, in which there is incorporated a main vacuum intake air bloweR coupled between the vacuum connection and a system air exit and a main compressed air blower coupled between a system air entrance and the compressed air connection, the arrangement comprising a single stand-by blower operatively coupled in said pneumatic system for maintaining system operation in substitution of either of said main blowers in the event of failure of either one of the latter, said stand-by blower being associated with said main compressed air blower by being coupled firstly in parallel to said main compressed air blower between said system air entrance and said compressed air connection, and being associated with said main vacuum intake air blower by being coupled secondly in parallel to said main vacuum intake air blower between said vacuum connection and said system air exit, said first parallel coupling including a first controlled valve coupled between the system air entrance and the air intake side of said main compressed air blower and a first back-pressure valve coupled between the compressed air side of said main compressed air blower and said compressed air connection, said second parallel coupling including a second controlled valve coupled between the compressed air side of said stand-by blower and the system air exit and a second back-pressure valve coupled between said vacuum connection and the vacuum side of said stand-by blower, and further comprising control means, including third and fourth back-pressure valves coupled respectively between the compressed air side of said main compressed air blower and said compressed air connection and between said vacuum connection and the vacuum side of said vacuum intake air blower, for detecting a failure of one of the main blowers and for activating said stand-by blower to an operative condition and the controlled valve associated with the failed main blower to an open condition. 